Factors Affecting the Gelation of a Gelatin Solution in the Presence of Sugar

Abstract

A series of measurements was conducted to clarify the mechanism for the sol-gel transition of gelatin in the presence of a variety of sugars that had been added to the gelatin solution. To investigate the effects due to the difference type and structure of the sugar, we measured the viscosity by a nondestructive method, the optical rotation, dynamic viscoelasticity, rupture characteristics and ¹⁷O NMR data. The gelation temperature was increased by added sugar. Physical changes during the sol-to-gel transition occurred in the following order : dynamic viscosity, dynamic elasticity, and then optical rotation each increased. Each gel of the gelatin solution with added sugar was stronger than that of the control without added sugar. The gel of the gelatin solution with maltose and trehalose added showed particularly strong ductility. The ¹⁷O-NMR spin-lattice relaxation time (T₁) of the gelatin solutions with added sugar, suggested that the number of equatorial OH groups (e-OH) in the 3D structure of the added sugar affected the gelation of the gelatin solution.